A huge amount of data processed and generated by business applications is kept in a storage system including a disk device having a large capacity, or the like, while periods during which the data should be kept vary depending on an attribute of each data, or regulations with regard to the data processing, statutes, etc.
Such a retention term of the data reaches not less than 10 years at the maximum, and may exceed a device life of storage apparatuses such as the disk device, the device life being usually approximately 5 years. When the storage apparatus that stores the data during the retention period of the data reaches the device life, it is necessary to copy the data (perform data migration) to other storage apparatus having a longer device life before a failure does not occur in the storage apparatus that stores the data so that the data can be securely accessed until the retention term expires.
From such a viewpoint, Japanese Unexamined Patent Application Publication No. 2006-350599 has proposed a technique, for example, in which several types of file groups whose last retention terms are going to expire are collectively managed, and migration is performed on the basis of priority of the storage apparatus, the device life, and the retention term of the file.
However, since time actually necessary for migration is not taken into consideration in the above-mentioned literature, there has been a problem that, for example, the storage apparatus of a data storage source may reach the device life while migration is performed, and secure data integrity by migration cannot be achieved.